This application claims benefit of Japanese Application No. 2001-126231 filed in Japan on Apr. 24, 2001, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to a centering mechanism of an electrically bendable endoscope, and an endoscope system, more specifically to a centering mechanism of an electrically bendable endoscope characterized by having a bending control portion at a bending segment, and to an endoscope system in which the bending of an electrically bendable endoscope is controlled.
2. Related Art Statement
Recently, endoscopes for examining the cavity of a hollow tube come to be widely used in medicine and in industries. When such an endoscope is used, the tip of its slender insertion segment is bent and inserted into the cavity of a hollow test tube. Bending the tip is achieved by directing bending effectors installed at the tip upward, downward, leftward or rightward appropriately via wires attached to the effectors.
Recently, an endoscope in which bending a bending segment is electrically achieved via wires attached to the segment through the driving of a motor installed close to the operator""s hand is proposed, for example, in EP0587506A1.
According to the conventional motor driving mechanism for bending the tip of an endoscope, it is necessary to connect wires to an actuator such as a motor for bending the tip, and, in order to insert the tip into a hollow test tube, to straighten the tip of the endoscope and to direct it squarely towards the mouth of the tube.
Thus, the tip of an endoscope should achieve a centering before insertion: the tip makes a continuous spiral turn, with the radii of sequential spirals being gradually decreased, until the tip is straightened and aligned with the mouth of a hollow test tube.
However, centering effected in the conventional endoscope has following problems. Namely, it is often impossible to straighten the tip of the endoscope so as to align it with the mouth of a hollow test tube because of inherent slackness and redundant lengths due to previous repeated over-stretching of the wires even if the tensions of the wires have been adjusted to 0 (zero) via an actuator. Moreover, if centering is effected in a limited space, the tip of the endoscope might bump against the surrounding tissue. In addition, centering might take an undue long time in such a space.
Accordingly, it is an object of this invention to provide a centering mechanism for an electrically bendable endoscope by which the tip of an endoscope can be straightened and aligned with the mouth of a hollow test tube at one stroke of motion, without being exposed to the risk of bumping against the surrounding tissue even when the centering is performed in a limited space.
It is another object of this invention to provide an endoscope system in which the tip of an endoscope can be straightened and aligned with the mouth of a hollow test tube at one stroke of motion, without being exposed to the risk of bumping against the surrounding tissue even when the centering is performed in a limited space.
The centering mechanism for an electrically bendable endoscope according to this invention comprises a bending segment attached to the endoscope, a driving unit for bending the bending segment, a bending instruction unit for giving an instruction for bending the bending segment, a centering instruction feeding unit for causing the previously bent bending segment to be returned to a straightened state, and a control unit which controls, in response to an instruction from the centering instruction feeding unit, the driving unit so as to cause the bending segment to be bent in a reverse direction to the currently bent state introduced in response to a previous instruction from the bending instruction unit, and then to be bent in a specified direction by a specified amount.
Other features and benefits brought about by this invention will become thoroughly apparent by referring to the following explanation.